The present invention relates to plasma display panels and more particularly to a compensation method for improving color purity and color temperature of plasma display panel by adjusting the strength of input image signals.
A manufacturing process of a conventional alternating current discharge type plasma display panel (PDP) 10 is shown in FIG. 1. First, two different activation layers are formed on glass substrates 11 and 12 respectively. Then seal the peripheries of the glass substrates together. A mixed gas consisting of helium (He), neon (Ne), and xenon (Xe) (or argon (Ar)) having a predetermined mixing volume ratio is stored in a discharge space formed in between the glass substrates. A front plate 11 is defined as one that facing viewers. A plurality of parallel spaced transparent electrodes 111, a plurality of parallel spaced bus electrodes 112, a dielectric layer 113, and a protective layer 114 are formed from the front plate 11 inwardly. From a corresponding rear plate 12 inwardly, a plurality of parallel spaced data electrodes 121, a dielectric layer 124, a plurality of parallel spaced ribs 122, and a uniform phosphor layer 123 are formed. When a voltage is applied on electrodes 111, 112, and 121, dielectric layers 113 and 124 will discharge in discharge cell 13 formed by adjacent spaced ribs 122. As a result, a ray having a desired color is emitted from phosphor layer 123.
Conventionally, in PDP 10 a plurality of parallel spaced transparent electrodes 111 are formed on inner surface of front plate 11 by sputtering and photolithography (or printing). Then a plurality of parallel spaced bus electrodes 112 are formed on the transparent electrodes 111 respectively by plating (or sputtering) and photolithography. The line impedance of the transparent electrodes 111 may be reduced by the provision of bus electrodes 112. In the following description, two adjacent transparent electrodes 111 (including bus electrodes 112) on the front plate 11 are represented by X electrode and Y electrode respectively. A triple electrode is formed by X electrode, Y electrode and corresponding data electrode 121 on the rear plate 12. When a voltage is applied on the triple electrode, dielectric layers 113 and 124 will discharge in discharge cell 13 formed by adjacent spaced ribs 122. Hence, UV rays are emitted from the mixed gas stored therein. And in turn, phosphor layer 123 in discharge cell 13 is activated by the UV rays. As an end, a visible light is generated by red, green and blue phosphor layers, resulting in an image showing.
In the conventional PDP 10, a mixed gas (which is a combination of neon (Ne) and xenon (Xe), a combination of helium (He), neon (Ne) and xenon (Xe), a combination of neon (Ne), xenon (Xe), and argon (Ar), or a combination of helium (He), neon (Ne), xenon (Xe) and argon (Ar)) is used. Note that neon (Ne) is the indispensable constituent component of any of the above combinations. When a discharge is occurred in any of the above combinations, an orange red of visible light Og having a wavelength of about 586 nm is generated as shown in FIGS. 2a and 2b. Note that the color of the visible light emitted during discharging may be one other than orange red if the combination of the mixed gas is changed. Such orange red of visible light generated by the gas in each of red, green, and blue discharge cells inevitably and adversely affects the color purity of PDP 10 and results in a lowering of color temperature of PDP 10.
Conventionally, as to the poor color purity and low color temperature of PDP caused by orange red of visible light during gas (mainly by Ne) discharging in discharge cell 13, a number of improvements have been proposed by PDP manufacturers to mitigate the above problems. For example, NEC (Japan) implements a capsulated color filter technique. A filter 20 on front plate 11 is formed on each of corresponding red, green, and blue discharge cells 13 as shown in FIG. 3. With this, it is possible to filter out the orange red of visible light Og from discharge cells 13, thereby increasing color purity and color temperature of PDP. However, the manufacturing cost is increased significantly because the manufacturing process of filters 20 is complex and the precision requirement is much higher. Another improvement technique is proposed by Matsushita (Japan) in which the sizes of red, green, and blue discharge cells 13 are made different one another as shown in FIG. 4. The size of blue discharge cell 13 is the largest among all discharge cells 13 for increasing color temperature of PDP. Also, the size of red discharge cell 13 is the smallest among all for decreasing the affecting degree on the color temperature of PDP. However, the manufacturing process is complex. Further, there is a great difficulty in driving such device.
In view of the above, such conventional improvements are disadvantageous for the complex process and undesirable design of PDP since the construction of PDP is changed for eliminating the adverse effect of the generated orange red of visible light on the color purity and color temperature of PDP. Thus, it is desirable to provide a novel method for improving color purity and color temperature of PDP in order to overcome the above drawbacks of prior art.
It is an object of the present invention to provide a compensation process for improving color saturation and image quality of a plasma display panel (PDP), wherein a brightness of light generated from each of red, green, and blue discharge cells of each pixel on said PDP is calculated through a numeric operation according to laws of color matching, the process comprising the step of increasing or decreasing the strength of input image signals of each of the red, green, and blue discharge cells in accordance with the calculation result for adjusting the brightness of the generated red, green, and blue lights so as to subtract a visible light generated by the gas in each of the red, green, and blue discharge cells during gas discharging, thereby eliminating an adverse effect of the visible light on color purity and color temperature of the PDP during gas discharging.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.